Cellulose Nanofibril‐Filled Damping and Lubricating Hydrogels for Mitigating Friction‐Induced Vibration of Polyurethane Composites

Achieving durable lubrication and effective damping, which are essential for suppressing friction-induced vibration and noise, remains a challenge in water-lubricated polymer friction components. In this study, a slippery multi-crosslinked polyvinyl alcohol (PVA) hydrogel (MCPH) was proposed based on PVA as the hydrogel matrix, carboxylated cellulose nanofibers as reinforcing agents, and various reversible interactions as efficient energy dissipation mechanisms. Subsequently, the prepared MCPH was blended with thermoplastic polyurethane (TPU), and a novel TPU/MCPH composite was developed. Friction and vibration experiments demonstrated that the incorporation of MCPH significantly enhanced the aqueous lubrication of the TPU composite, which was attributable to the synergistic effects of the improved hydrophilicity, water absorption/release functions of MCPH, and hydration lubrication. Moreover, the reversible interactions within MCPH were continuously disrupted and rapidly reconstructed under frictional shear stress, enabling efficient mechanical energy dissipation and enhancing the damping capacity of the TPU/MCPH composite. Consequently, under the synergistic effects of improved lubrication and enhanced damping capacity, the modified TPU composite exhibited a low coefficient of friction of 0.109 under aqueous conditions and a substantial reduction in vibration and noise responses. This innovative composite provides a promising strategy for developing high-performance polymer friction materials with superior lubricity and vibration-noise suppression under aqueous environments.